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Lake effect, and maybe some accumulating snow: A day by day look through this week

Fall 2011.JPG

A light snow cover in Tully, New York the third week of October 2011. In October of 2011 and again in 2012, snow fell over communities in higher elevations south of Syracuse.
(Dave Eichorn | deichorn@syracuse.com)

The cold weather we spoke about last week is starting to pour southeast over the upper Great Lakes. It's snowing over upper Michigan and northern Wisconsin right now. This out of season chill will overspread Central New York in stages.

The first wave of this new air will arrive in Central New York Tuesday morning. Another will arrive Wednesday.

Each reinforcing push of colder air will bring our temperatures down and by Thursday, our daytime high temperatures will be around 10 to 15 degrees below normal for mid October.

The air coming in this week will be unusually cold for October, especially in the upper atmosphere.

By Wednesday morning, the air just 10,000 feet above us will be a frigid 10 degrees F above zero or colder. That kind of air over the 62 degree water of Lake Ontario will create a very unstable atmosphere.

There will be snow.

Inland areas away from the warm water of Lake Ontario will be the most likely areas for snow. It is possible that by mid week, the snow will begin to accumulate under localized bands of lake effect over higher elevations.

The lake effect rain and snow may be locally heavy at times this week. Lightning and thunder will be possible near the lake. More waterspouts are possible over the lake this week as well.

Here is a day by day rundown of this week's weather.

View full sizeWeather map for Tuesday evening. The white shaded areas near the Great Lakes show the most likely areas for lake effect rain and higher elevation snow.Dave Eichorn | deichorn@syracuse.com

Tuesday's weather map is showing much cooler air will build in over the eastern Great Lakes. By the end of the day the air over Central New York will be cooling from the 50s down into the 40s. Rain showers will be mixing with snow showers over higher elevations north of Syracuse, east of Lake Ontario.

Tuesday night, localized areas of lightly accumulating snow are possible over the northern Tug Hill and the western Adirondacks.

Wednesday:

Wednesday's weather map shows a small change in wind direction as another reinforcing push of the cold air will moving in over the eastern Great Lakes. Winds may start off from the west-southwest during the day but will become more westerly later in the day. This will cause the more concentrated areas of lake effect rain and snow to shift farther south over the counties east of Lake Ontario

Accumulating snow is possible well inland from the warm lake, most likely at elevations above 1000 feet.

Thursday and Friday:

The cold air will deepen over the Eastern Great Lakes. Thursday's weather map shows winds becoming more northwesterly. This means that the lake effect will be shifting farther to the south closer to the Syracuse area.

Most of the snow early this week will be in the form of snow pellets (called graupel). However, as the temperature gets colder later in the week, real flakes of snow may start coming down.

If Lake Huron establishes a "connection" to Lake Ontario later in the week, then both lakes could develop a stronger band of heavier snow. We'll be keeping an eye out for that possibility Thursday night or Friday.